stdafx.h and const char* error
 

I was creating a C program for creating Windows Socket, using Visual Studio 2010. I got the following errors while trying to compile it:

1. error C1083: Cannot open include file: 'stdafx.h': No such file or directory [For the line, #include <stdafx.h>]

2. IntelliSense: cannot open source file "stdafx.h" [For the line, #include <stdafx.h>]

3. IntelliSense: a value of type "const char *" cannot be assigned to an entity of type "char" [For the line, buf[0] = " ";]

How to fix those problems, I tried google and solved other 4 errors but these three are being headache for me, I have just started Win32 Application in C so I don't have deep knowledge. I am waiting for your help.